Uncertainty for uncertain decision makers

First Chapter - While mainstream decision theory only allows for variations in the severity of uncertainty, the plurality of labels with which uncertainty has been referred to in the literature and the variety of doubts that decision makers can have seem to suggest that there are different types of uncertainty. Given the importance that uncertainty has in almost any decision, understanding this plurality can be helpful to decide effectively. I propose an account of uncertainty as based on a disagreement between reasons supporting alternative mental attitudes. Under this account, dealing with uncertainty means dealing with disagreement; however, this disagreement can be radical, i.e. persistent under ideal cognitive and epistemic conditions. When this is the case, the disagreement and therefore the uncertainty cannot be resolved with an increase in evidence. I draw a typology of uncertainty reflecting the conditions that must obtain for the possibility of radical disagreement, and I trace the role that each of the types identified plays in decision making.